1. what spell?
2. what names?
3. what dragon are you calling?
4. what 'dragon being of great power'?
a spell to change your eye colour, with or without dragons, won't work because magic doesn't work that way. perhaps an illusion spell might make your eyes appear a little greener, but you're not actually changing the colour. if you're talking about the dragon sight spell, it doesn't give you the eyes of a dragon, it will help your clairvoyance to sense danger better.
Dragon Magick is a form of high magick, past down verbally from dragon to student, then from one practitioner to another in the same clan, rarely from one person to another. Dragon Magick can be extremely dangerous for those who don't have experience with magic, haven't studied dragons, astral projection, grounding, shielding, circle casting... people who practice Dragon Magick normally don't begin until after they have studied magi for a couple years.
you can welcome dragons into your life simply, leave out offerings like coins, feather, pearls, depending on what type of dragon you wish to call forth. just because you're open and welcoming, doesn't mean a dragon will come to visit a few minutes later. not only are they astral beings who spend far more time there than wandering around here in the physical, they're cautious and untrustworthy of humans [heard of some who aren't but that's very rare] so it could take years before one comes to stay. i have practiced for almost five years now, and barely a year ago did my first dragon come to my house. [mind you i've met them in the astral, i mean stay in my house]
how you'll know it works really depends on the dragon. if there's a fire dragon, the room it's in will seem much hotter, an air dragon will increase the rooms humidity, a water dragon would make the room feel cool and damp, and so on. most dragon guardians who live in [or visit] your house though are small, about the size of a house cat on average. they're energetic, and typically knock stuff over. you can see dragons better while meditating though, some people use crystals, or other skrying tools to help them see better.